A first group of prior art two-wheel self-balancing vehicles is represented by a product known commonly as the “Segway.” This product is disclosed in U.S. Pat. No. 6,302,230, issued to Sramek et al (the '230 patent). While a contribution in the field, the Segway and like devices are disadvantageous in that they are large, heavy and expensive, i.e., too heavy to be carried by a commuter or youth, too expensive for most to buy. Furthermore, turning is achieved through a handle bar structure that ascends from the platform upward toward the chest of a user. This tall steering structure is a trip hazard when a user makes an unplanned exit from the vehicle.
Another group of prior art two-wheel self-balancing vehicles has two platform sections, each associated with a given wheel, that tilt from side-to-side as a user leans left or right. The two platform sections move in a linked or “dependent” manner (for example, through a parallelogram frame, and not independently) and there is a single “vertical” axis for the platforms. When the axis is tilted directly forward or backward, both wheels drive at the same speed (as required for self-balancing). If a user leans to the side (tilts the “vertical” axis sideways), then the outside wheel is driven faster than the inside wheel to effect a turn toward the direction of the tilt.
These devices typically require a multi-component parallelogram structure to coordinate/link movement of the two platform sections and the wheels. Such componentry adds to the weight, bulk, complexity, and potential for mechanical failure of the device. Also, the turning radius is fairly large as one wheel is typically rotating around the other (moving in the same direction though at different speeds).
A need exists for a two-wheel self-balancing vehicle that provides independent wheel control, is light-weight and compact, is easy and safe to use, and that may be made in a cost-effective manner. A need also exits for a two-wheel self-balancing vehicle that is more maneuverable and more ergonomic (functioning more naturally with the bio-mechanics of a user's legs and body) than prior art devices.
Other prior art includes skateboards that have two platforms sections that are movable with respect to one another. Some have a shared shaft about which the two platform sections pivot, while others have a degree of flexibility in the platform. In both of these arrangements, the platform sections are arranged longitudinally, one primarily behind the other in the longitudinal line-of-direction of travel.